From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53980) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ae4Ze-00084X-4P for qemu-devel@nongnu.org; Thu, 10 Mar 2016 12:40:38 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ae4Zd-0005eu-8q for qemu-devel@nongnu.org; Thu, 10 Mar 2016 12:40:34 -0500 Received: from mx1.redhat.com ([209.132.183.28]:58589) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ae4Zd-0005ep-3c for qemu-devel@nongnu.org; Thu, 10 Mar 2016 12:40:33 -0500 References: <1454151394-52320-1-git-send-email-vsementsov@virtuozzo.com> <20160203081418.GC25746@ad.usersys.redhat.com> <56B45D3A.405@virtuozzo.com> <20160209142852.GA13149@stefanha-x1.localdomain> <56B9FAAE.8040503@virtuozzo.com> <20160210101004.GB7317@stefanha-x1.localdomain> <20160216170943.GA31393@stefanha-x1.localdomain> <56C4B21F.9030006@virtuozzo.com> <20160218121114.GC12470@redhat.com> <20160218164148.GB13271@stefanha-x1.localdomain> <20160219020826.GA23506@ad.usersys.redhat.com> <87povtulpt.fsf@blackfin.pond.sub.org> <56D0ADBD.20000@redhat.com> <87vb583pci.fsf@blackfin.pond.sub.org> <56D40759.8000500@redhat.com> <56D4127E.60908@redhat.com> From: Paolo Bonzini Message-ID: <56E1B18B.90307@redhat.com> Date: Thu, 10 Mar 2016 18:40:27 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2 0/6] external backup api List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: Kevin Wolf , Vladimir Sementsov-Ogievskiy , Fam Zheng , "Denis V. Lunev" , qemu-devel , Markus Armbruster , John Snow On 10/03/2016 18:37, Stefan Hajnoczi wrote: > I suggest giving the new NBD command a "type" argument: > 0 - SCSI mapped/anchored values according to SCSI Get LBA Status > 1 - Dirty/clean, useful for incremental backup and other blocking tracking cases > > This way we don't impinge on SCSI semantics and the command can be > used for both traditional logical block provisioning and dirty bitmap > info. > > When the NBD export is started in QEMU you can optionally associate it > with a bitmap. This bitmap is used to provide type=1 (dirty/clean) > status information. Good idea. The precedent in NBD is to use bits 16..31 of the command for flags, so it could go there. Paolo